Just finished the 2A3 tube amp project. I need few days for fine-tuning. I will provide more information soon. So stay tuned. In the meanwhile watch the related video.
Direct heated triode power output tubes are really interesting. Since September 2008 I've been working in a new project regarding a single ended triode tube power amp using the 811A vacuum tube. Actually it is a project with a long process of experimentation.
The 811A vacuum tube it is a power triode capable to output 10 - 15 Watts in a single ended class A2 configuration, in a three stages circuit using interstage transformer in the driving stage.
Giannis Spathopoulos made this one-off treasure audio power amp. This prototype model featuring four JJ EL34 power output pentodes per channel in an ultra linear push pull configuration. With an ECC83 as a pre stage, an ECC85 as a phase splitter, and a 6FQ7 as a buffer, this extremely dynamic and sweet sounding design is rated at 30 Watt in a class A configuration, and 70W in a class AB1 configuration.
Making a low power single ended amplifier has always been in my designing plans. Obviously such a construction requires the appropriate speakers, particularly horn type designs, so that the output of the amp can reach an efficiency satisfying level.
Once at a certain point, I came across the designs of the Decware SE EL84 Zen amp, which had quite good reviews among the tube amps DIY and Single Ended tube amp builders.
Even though 6L6 tube is used primary in guitar vacuum tube amplifiers, many manufacturers use this tube in audiophile designs. I decided to build this small single ended amplifier based on 6L6 vacuum tube using a classic three stage single ended design.
The idea of building a DIY audio vacuum tube amplifier based on high-quality materials begins in the early 90's. Initially had to answer the question "Classic Push Pull or a Single ended amp ?" So starting the design somewhere in 1994 I decided to design οn a blank piece of paper, a pair of monoblocks push pull tube amps with a power supply in a separate chassis which would not use solid materials but rectifier tubes.
This project was an attempt to build a tube amplifier power supply for my 6550 push pull dual mono amps. I already had a really ugly tube power supply in my rack and in early 2000 I decided to design and build from the scratch a new tube PSU.
In the summer of 2002 I decided to build a pair of mono block parallel single ended DIY tube amps, using the 807 tube. Actually, that was my third DIY tube amplifier project. It all started with my decision to use the less known tube 807 , a tetrode whose features and sounds I was well aware of, from a specific DIY project (with one tube per channel wired in triode) made by Christos Spathopoulos.
This gorgeous heavyweight SET amp uses the Direct Heated 813 tubes triode connected, runing at 120mA. OPTs are the excellent Sowter SE18 SE.
The filaments power supply uses batteries for eliminating hum.
The main power supply uses a toroidal Amplimo Power transformer (850V secondary), followed by an CLCLC filter separately for each channel using polypropylene and oil capacitors only.
What we have here is an acrylic stereo, 5u4GB tube rectified, Single Ended Triode using two 6L6Gb’s as outputs, one 6CG7 and one 12AX7. It’s powered by a Stancor Power transformer I had on hand, one very beefy Hammond choke, and two 5K Edcor OPT’s which are rated at 15 watts.
